According to a conventionally known technique, in a communications apparatus, power is supplied to a wireless communications unit only when communication is performed and during standby, power is supplied to only a communication invoking signal receiving unit that has low power consumption, whereby power consumption is reduced (for example, refer to Japanese Laid-Open Patent Publication No. 2003-174382). Further, according to another known technique, concerning a microprocessor, by transitioning from an active state to a power-off state or a standby mode, power consumption is reduced (for example, refer to Japanese Laid-Open Patent Publication No. 2010-114484).
Wireless sensor networks (WSN) are further known in which plural sensor-equipped wireless terminals are interspersed in a given space and work in concert to enable environmental and/or physical states to be obtained. For example, by equipping the wireless terminals with a battery and a capacitor, the battery life can be improved (for example, refer to Japanese Laid-Open Patent Publication No. 2008-148124).
Further, for example, according to a known technique, at each wireless terminal, the power generated by an ambient energy harvesting apparatus of the wireless terminal is stored; and an apparatus that aggregates information from the wireless terminals detects the amount of power generated and stored by each terminal, and manages the operating state of each terminal (for example, refer to Japanese Laid-Open Patent Publication No. 2011-13765).
For example, according to another known technique, a terminal that can move about in a sensor network has an energy storage unit that can store electrical power, and the terminal moves about supplying electrical power to other wireless terminals (for example, refer to Japanese Laid-Open Patent Publication No. 2007-97358).
Further, according to another known technique, an apparatus that aggregates information from wireless terminals is equipped with a solar panel (for example, refer to Japanese Laid-Open Patent Publication No. 2011-155556).
Nonetheless, at a terminal that is charged by the electrical power generated by the terminal and executes data processing by using the charged electrical power, execution of the data processing may be suspended if the electrical power is depleted. In this case, the execution of the data processing is resumed after waiting for charging of electrical power to execute the data processing and therefore, completion of the data processing is delayed.